Automatic centerhead



Aug. 4, 1936. E. H. EADY AUTOMATIC CETERHEAD Filed July 18, 1954 2Sheets-Sheet lll/lll Aug.v4, 1936. 4 E. H. EADY 2,050,090

AUTOMATIC CENTERHEAD Filled July 18, 1934 r 2 Sheets-Sheet? Arme/VDPatented Aug. 4, 1936 UNITED STATES PATENT OFFICE AUTOMATIC CENTERHEADApplication July 18, 1934, Serial No. 735,757

9 Claims.

The present invention relates to an automatic centerhead of improvedstructure.

Among the objects of the invention are the following:

An improved construction for a collet;

Improved means for operating a collet;

A more convenient centerhead and having readily accessible operatingmeans;v

A collet construction in which there is little or no axial thrust;

A collet which may run in closed or open position with relatively slightfriction.

These objects, and such other objects as may hereinafter appear, areobtained byV the novel construction, unique combination, and improvedarrangement of the several elements constituting the invention, one formof which is illustrated in the accompanying two sheets of drawingshereby Vmade a part of this specification, and in which:

Figure 1 is a plan view of an apparatus embodying the subject matter ofthe present invention, a portion of the housing about the collet beingin section;

` Figure 2 is a vertical section of the collet, the

bracket, and the support for the bracket;

Figure 3 is an end elevation of the support for the bracket shown inFigure 2; Figure 4 is a front elevation of the complete device, a partof one side being broken away and in section to illustrate details ofstructure; and

Figure 5 is a side elevation of the complete device, one cover platebeing removed to show the rack bar, pinion, and cam by which the presentdevice may be operated.

Like reference characters are used to designate similar parts in thedrawings and in the following description of the invention.

The device is intended for use upon a lathe.

Fragmentary portions of frame members of a lathe are indicated IIJ andII in'Figure 4, the member I0 having a rib- I2 on the upper surfacethereof.

'I'he centerhead has a base I3 supported upon the members I0 and II,there being in the base I3 a groove III complemental to the rib I2. Anyother means for holding the centerhead on a lathe and preventingtransverse movement of the base I3 thereon may be substituted for thatshown.

There is a bolt I5 at the center of the base I3, the bolt I5 having anelongated shank, the lower extremity of which is threaded. A plate. I6shown in Figure 4 may be employed in conjunction with the nut I 1 tosecure the centerhead base firmly upon a lathe.

Base I3 may be generally rectangular in plan View and it has at one sidean upright section I8. The upright section I8 comprises two reinforcedsections having vertical slots therein. Between the end sections is aweb I9. The slots vIl 20 are parallel and are for the purpose ofproviding vertical adjustment for a bracket attached to the base I3. Y

Secured to the upright section I8 is a bracket 23 which may be of anysuitable form and which 10 is shown with a lower. section having studs2I anchored securely therein, the studs 2| penetrating the slots 20 andthe bracket being secured in position upon upright section I8 by thenuts 22.

At the sides of the bracket 2s are two uprights 15 24 which provide ahousing for rack bars,.later to be described. Between the members 24 andat the top thereof is a sleeve or bearing 25. Within the sleeve orbearing 25 is a bushing 26 `which has a flanged end 2'I limiting itsmove-- 20 Y ment in one direction.

Journalled within the bushing is a spindle 28 which has a collar 29engaging the iianged end 2l of the bushing 26 to limit axial movement ofspindle 28 in one direction. Atv the other end of the bearing 25, thespindle 28y has a lock-ring yor collar 30 held inv position by a setscrew 3| for preventing axial movement of the spindle in the oppositedirection. 'I'he spindle 2K8 is freely rotatable.

The spindle 28 has a slightly enlarged internal 30 section 32terminating in a threaded portion 33. Into the sections 32 and 33 theremay be inserted a drive shaft 34 having a threaded end, the drive shafthaving a collar 35limiting its pene- 35 tration of the spindle 28.

At its other end the spindle 28 has about its periphery a anged housing,later to be described. The spindle 28, as shown, is of asubstantiallyuniform external diameter to the right of collar 29, Figure 2.

The spindle 28 is hollow throughout its length. The central aperture isof substantially uniform -diameter until the right hand end, Figure 2,is f approached. A slightly enlarged section 36 which 45 the shoulder 38being radial of the 50 The grooves 4I and 42 55` il.

are separated by a flange or collar 43. The outwardly extending portionof the collet is divided into grip pieces 44 by two diametric slots 45and 46 normal to one another and extending from the outer face inwardlyinto the outermost of the grooves 42, the outer edge of each segment ofthe collet having a peripheral flange 41. The collet 39 has asubstantially uniform aperture 48 axial thereof. The opening 48 issubstantially the size of the work to be held therein.

Between the collet 39 and the adjacent wall of the spindle 28 is atapered sleeve 49, the exter nal portion of which is of substantiallythe same diameter as the interior of section 31 of the spindle 28.Interiorly, the tapered sleeve 49 has a truly cylindrical aperture 50which fits over the grooves 4| and 42 and flange 43 of the collet and atapered section 5| which ts over the tapered section of the collet.

The truly cylindrical section 50 has a plurality of tap holes 52 toreceive pins 53. The pins 53 have a main body 54 and an end 55 ofreduced section to fit into the holes 52 in the tapered sleeve 49. Thebody 54 of the pins fits into a ring 56 rotatable with the spindle 28but movable longitudinally thereof.

To provide a track for the bodies 54 of the pins 53 during theirmovement longitudinally of the spindle 28 when the ring 56 is moved,elongated slots 51 are formed in the wall of the spindle 28. The wall ofeach slot 51 engages one side of a pin 53 to rotate the pin 53 with thespindle 28 and to cause rotation of the ring 56. The slots 51 restrictthe movement of the ring 56 along the spindle in either direction to adefinite linear path.

About the ring 56 is a flanged housing 58, the peripheral portion ofwhich fits loosely about the periphery of the ring 56. The housing 58has a flange portion 59 which engages the left wall of the ring 56(Figure 2). Covering the open side of the housing 56 is an annularmember 60 which is fastened to the housing by screws or in any othersuitable way and which engages the right Wall of the ring 56 (Figure 2)At opposite sides of the housing, as shown in Figures 1 and 4, arebosses 6| through which there are apertures parallel to the spindle 28.Into each aperture there is inserted a stud 62, each stud 62 having areduced end which is adapted to be riveted into a countersunk section(not shown) in the outer end of the boss 6|.

Studs 62 extend to the left in Figure 1 and through bosses 63 and 64which form bearings, the bosses 63 and 64 being at opposite sides of theupright sections 24 of the housing containing the rack bars. In thismanner the housing 58 for the ring 56 is held against rotation, but isreadily movable coincidently with the movement of the studs 62 alongtheir axes.

Each stud 62 has a transverse opening therein into which a pin 65 isdriven. Upon one end of the pin 65 or upon both ends thereof, ifpreferred, a roller 66 is mounted. In the slots there- .for ln thehousing sections 24 are two rack bars 61. Each rack bar 61 has a mainbody, a depending narrow section in which a rack 68 is formed, and anupwardly extending bifurcated section 69, the bifurcations beingseparated by a width equal ,to that of a stud 62. In one or both of thefurcations 69 there is a. slot 10. The slots 10 are oblique and paralleland house the rollers 66. As bars 61 are moved up and down in thehousing 24, the studs 62 are moved forwardly 0r backwardly according tothe direction of the movement of the rack bar 61.

For actuating the rack bars 61, pinions 1| engage the rack 68. Thepinions 1| are keyed to a shaft 12 which is arranged transversely of thebracket 23 and is journalled in the opposite sides thereof. At one endof the shaft 12 is a collar 13 through which a handle socket extends,and at the other end of the shaft is a collar 14 secured in position bya lock-pin, the two collars 13 and 14 preventing axial movement of theshaft. Into the handle socket in collar 13 a suitable handle 15 isinserted. Other means for actuating the housing 58 may be substitutedfor the rack and pinion shown and described.

From the description given, the operation of the device is clear. Thespindle 28 is rotated with the rotation of the drive shaft 34. Thecollet 39 is open or closed according to the position of the handle 15which, if moved in one direction, rotates the pinion 1| to move the rackbar 51 which in turn engages the roller 66 and by a camming action movesthe stud 62 forwardly or backwardly, the movement of the stud 62 beingcommunicated to the housing 58 and by the housing to the ring 56 uponthe exterior of the spindle 28, and from the ring 55 to the pins 53 andfrom the pins 53 to the tapered sleeve 49 which surrounds the collet 39.Movement of the tapered sleeve 49 to the right in Figure 2 will closethe collet. Movement to the left will open the collet. The collet isadapted to be closed upon a piece of work, such as the bar 16 shown inFigure 1.

The ring member illustrated an-d described when combined with the colletshown has a pronounced advantage in running with slight friction whetherin open or closed position. The device, because of its symmetricalarrangement, is self-centering. As described, all of the operatinghandle is instantly accessible and in the most convenient position forthe operators use. The thrust of the collet during operation is soslight that it is insufficient to change the adjustment of the partsduring running, hence there is no tendency of the work 16 to free itselffrom the centerhead.

What is claimed as new and is desired to be secured by Letters Patent ofthe United States is:

1. In a centerhead having a collet in a spin dle, a sleeve movablelongitudinally of the collet, a ring about said spindle and movablelongitudinally thereof for moving said sleeve, a housing for said ringthereof, and means for holding said housing against rotation during therotation of said ring and for moving it longitudinally of said spindleto move said ring.

2. An automatic centerhead comprising a base having means of attachmentto a lathe, a bracket secured to said base, a spindle journalled in saidbracket, one end of said spindle having means of attachment to a driveshaft and the other end of said spindle having a hollow section, therebeing longitudinal slots in said spindle intermediate its ends, a collethaving a cylindrical body and segmental jaw members integral with saidbody, the cylindrical body being secured to said spindle and the outerwalls of said jaw members being tapered, a tapered sleeve about said jawmembers and movable longitudinally in said hollow section of saidspindle, pins in said sleeve 70 ing for said ring and having side wallsengaging 75 the sides of said ring, brackets on said support, studsslidably disposed in said bracket and secured to said housing to preventits rotation, and means for moving said studs axially of said spindle todetermine the position of said ring therealong.

3. In a centerhead having a support, a spindle, a collet, means in saidspindle to adjust said collet, and a ring about said spindle andmoveable axially thereof to operate said means, a housing about saidring, brackets on said support, studs slidably disposed in said bracketsand secured to said housing, racks on said support and having angularlydisposed slots therein, pins on said studs and sliding within saidslots, and pinions to move said racks.

4. The device described in claim 3, and in which said racks havebifurcated ends straddling said studs.

5. In a centerhead having a collet in a spindle, a sleeve movablelongitudinally of the spindle for operating the collet, a ring about thespindle operatively connected with said sleeve and movablelongitudinally of the spindle to move said sleeve, a housing for saidring, means for holding said housing against rotation and adapted fortransmitting longitudinal movement to said housing, pins on said holdingmeans, slot containing means having angular slots to receive said pins,and rack and pinion means to. move said slot containing means, themovement of said means being transmitted to said sleeve to operate thecollet.

6. A supplementary centerhead for use on a lathe having a spindle,comprising a support adjustably mounted on the lathe bed, a bearingsubstantially integral with said support, a spindle in said bearing andattachable to said first spindle for rotation therewith, and centeringand holding means in said second spindle.

7. A supplementary centerhead for use on a lathe having a spindle,comprising a base adapted for mounting on the lathe bed, a bearingsupport adjustably secured to said base, a bearing substantiallyintegral with said bearing support, and a. supplementary spindlejournaled in said bearing and adapted to be secured to the lathe spindlefor rotation therewith.

8. A supplementary centerhead for use on a lathe having a spindle,comprising a base adapted for mounting on the lathe bed, a bearingsupport, bolt and slot means for adjustably securing said support tosaid base, a bearing mounted on said bearing support, and asupplementary spindle journaled in said bearing and adapted to besecured to the lathe spindle for rotation therewith.

9. A supplementary centerhead for use with a lathe having a spindle,comprising a base adapted for mounting on the lathe bed, a bearingsupport, means for adjustably securing said bearing support to saidbase, a bearing mounted on said bearing support, a supplementary spindlejournaled in said bearing and adapted to be secured to the lathe spindlefor rotation therewith, centering 30 and holding means in thesupplementary spindle, and means carried by said bearing support foroperating said centering and holding means.

ERNEST H. EADY.

